It is possible to say that the performance of a semiconductor device today largely depends on the accuracy of a fine processing (i.e., reducing the minimum feature size in semiconductor integrated system) through a semiconductor lithography technology (See FIG. 12). In a fine processing using a conventional lithography technology with light (electromagnetic wave) of a visible light band, the wavelength of light determines the resolution. Accordingly, as shown in FIG. 13, in order to achieve a finer processing, it is necessary to use light of a shorter wavelength band than a visible light region; e.g. EUV (Extreme Ultraviolet Rays) or X ray.
However, it is not easy to design a device for generating light of such a short wavelength band, or an optical system for focusing the light beam which is patterned by reticle.
For this reason, there has been a suggestion to use an electron beam (electron ray) in a fine processing by a semiconductor lithography technology, on the grounds that an electron beam is relatively easy to generate or control, though it is difficult to tailor diverging lens.
However, a semiconductor manufacturing (lithography) device adopting an already-existing electron beam directly draws a circuit pattern of a semiconductor device with a use of a single electron beam. Accordingly, a large amount of irradiation time (several hours to several tens of hours) is required to draw an entire circuit pattern of a highly-integrated semiconductor device. In other words, a wavelength-dependent electron beam irradiation method for breaking through the limit of the fine processing is one dimensional exposure method for a practical. Therefore, a large amount of exposure time should be reduced and the development of two-dimensional irradiation is required.
In recent years, in order to shorten the irradiation time of electron beam lithography, a two-dimensional irradiation method which collectively forms a two-dimensional electron beam pattern have been developed. Examples of such two-dimensional electron beam collective irradiation methods are called SCALPEL method developed by AT&T and PRIVAIL method developed by IBM.
In the SCALPEL method as shown in FIG. 14(a), an electron beam 31 is projected on a reticule 32 having a dispersing section 32b which have device pattern on the surface of a membrane 32a. Through an optical system having an electronic lens 33 and a back focal plane filter 34, the emitted electron beam is projected on an electron ray resist. Thus, a circuit pattern is formed. This SCALPEL method is also described in Patent Citation 1.
As shown in FIG. 15(a) and FIG. 15(b), in the PRIVAIL method, an Si substrate 44 on which a hole 44a is formed according to the pattern is used as a reticule. Toward this patterned Si substrate 44, an electron beam 41 is projected. Through an optical system, the electron beam 41 having passed the hole 44a is projected to an electron ray resist, thereby exposing the wafer to the beam. Examples of the optical system in PRIVAIL method are: an electronic lens 42; an illumination lens 43 having a yoke for polarizing an axis of the electron beam; a collimation lens 45; and a projection lens 46 having a contrast aperture 46. Note however that the PRIVAIL method is not able to manufacture an Si substrate 44 having a hollow portion as shown n FIG. 15(c). Patent Citation 2 describes the PRIVAIL method.
(Patent Citation 1) U.S. Pat. No. 5,260,151 (Date of Patent: Nov. 9, 1993)
(Patent Citation 2) U.S. Pat. No. 5,466,904 (Date of Patent: Nov. 14, 1995)